1. Field of the Invention
The invention is relevant to the field of connector- or interface technology for testing integrated circuits (IC), e.g. computer chips and microprocessors, and relates to a cable interface for a plurality of coaxial cables.
2. Discussion of Related Art
Processors used in commercially available computers have an ever increasing number of connections. Up to 1024 connections, which are used for transferring data and/or energy to and from a processor core, are expected in the future. The frequencies at which the data are transferred is in the gigahertz range. The functionality of every IC is checked and tested between the various production steps and at the final inspection. For this purpose, testing apparatus containing a load board are known from the prior art. In these load boards, a large number of serial connections are led from a test head to a measuring station. Currently, data rates of up to 6 Gbps are typically achieved. In the future, data rates of up to 15 Gbps or more are expected. Owing to the limited amount of space available on the load board and to the PCB (printed circuit board) connections, which are preferably as short as possible, 100 channels per square inch are advantageous.
Connectors or cable interfaces for testing chips that have a plurality of connections, which are inserted into load boards, are known from the prior art.
WO10063588 from the same applicant was published on Jun. 10, 2010 and concerns a three-dimensional test adapter (load board) for computer chips. The test adapter is suitable for a cable interface having a high connection density.
U.S. Pat. No. 7,364,461B from SV Probe PTE LTD was published on Apr. 29, 2008 and concerns what is known as a probe card assembly (PCA) which is used to test computer chips. The PCA has a main body having blind holes. Openings are provided at the end of the blind holes for receiving the inner conductors. Conductive elements, which are separate from said inner conductors, are arranged on the side of the blind holes. In order to be attached, the cables must be accessible from both below and above so that they can be soldered. As a result, high component densities are not possible.
U.S. Pat. No. 6,686,732B from Teradyne Inc. was published on Feb. 3, 2004 and concerns an inexpensive interface module. A so-called stiffener has a plurality of bores for receiving cables. The stiffener has a planar end face to which a substrate is bonded for signal transmission. The design of the connector is relatively complicated and said connector is not suitable for high component densities.
U.S. Pat. No. 7,816,932B from Teradyne Inc. was published for the first time in 2009 and concerns what is known as an interposer. The interposer has a housing which is made of a non-conductive material and a plurality of chambers which are arranged in a grid-like manner and in which conductive elements, e.g. made of wire, are arranged in one direction. The interposer is suitable for transferring high-frequency signals between a test device and a device being tested. For this purpose, the interposer is arranged between said two devices.
U.S. Pat. No. 7,815,466B from Teradyne Inc. was published in 2009 and relates to a cable interface for a plurality of coaxial cables. The cable interface has a base plate which is made of a non-conductive material and into which holes of different diameters are drilled. Non-continuous holes (blind holes) are used to receive stripped cables which are inserted into the plate from one side. The inner conductors of the cable are connected to the opposite side of the plate in an electrically conductive manner. For each blind hole, continuous holes are provided which extend at the side of said blind hole and parallel thereto, and which are each connected to one single blind hole.
Both the blind holes and the continuous holes are coated so as to be electrically conductive. The continuous holes are filled with tin solder or another material. Depending on the construction, each blind hole has continuous holes assigned thereto. The result of this is that the principle allows only a relatively low component density. In addition, this interface is difficult to produce as the arrangement of the conductive surfaces and regions is not optimal.
In conventional individual HF connectors, the soldering site around the cable and the connector is in principle freely accessible so attaching the cable to the connector is not a complex process. This can no longer be done in a simple manner in a cable interface with a high component density, since the cables are in very close proximity to one another.